Overweight and obesity are highly prevalent among people with severe mental illness (SMI); these conditions in the SMI likely contribute substantially to hypertension, diabetes mellitus, coronary disease, and early mortality. Through increased appetite and other possible mechanisms, most a typical antipsychotics cause weight gain. Yet, given their effectiveness and fewer neurologic side effects, these medications will likely remain a mainstay of pharmacotherapy in the foreseeable future. At the same time, weight gain may play a role in non-adherence to antipsychotics. Effective behavioral weight loss interventions exist for the general population; however, they are probably not appropriate for people with SMI, who have special needs. Healthy lifestyle interventions for people with SMI are urgently needed. Psychiatric rehabilitation programs provide a unique context for testing nutrition and exercise interventions through their emphasis on skills building in a supportive environment. In this R34 application we propose a pilot study with three aims: 1) Design a healthy lifestyle intervention for psychiatric rehabilitation clients that is based on state-of-the art interventions for the general population, incorporates client input, and is appropriately adapted to client needs; 2) Test the intervention's feasibility and preliminary efficacy; and 3) Use pilot data from this study to develop an R01 application for a full-scale randomized controlled trial of the intervention. The multifaceted intervention will combine skills training and environment/social support through a) healthy modification of on-site meals; b) nutrition and exercise behavioral counseling; and c) on-site exercise. We will enroll 50 clients and measure whether the 6 month intervention leads to: a) 10 pound weight loss; b) regular moderate physical activity; and c) improvement in quality of life, health status and mental health. This R34 will provide valuable pilot data for future work to improve healthy lifestyles and reduce chronic medical illness in people with SMI.